The present invention relates generally to fabrics, products, and methods of producing such fabrics and products. More specifically, this invention relates to absorbent warp knitted polyester fabrics and methods of producing such fabrics and products.
In warp knitted fabrics, it is known that to create a plush raised surface on its technical back, one set of warp yarns must be knitted in a stitch pattern to produce and extended underlap of yarn on the technical back of the fabric. The technical back can then be brushed to allow the individual fibers of the yarn to be broken and raised to form a plush face. Often, these fibers must then be sheared, in an additional step, to produce a uniform plush face yielding a velour-like effect. However, problems may be encountered with the durability of these fabrics, in that the weakened structures may be susceptible to unwanted performance characteristics such as stretch, creep, and pilling.
U.S. Pat. No. 5,916,273, hereby incorporated by reference, describes an improved warp knitted plush fabric, and method of producing same, whose construction is uniquely suited to resist unwanted performance characteristics such as stretch, creep, and pilling. Briefly described, the desired properties are achieved by using special ground and pile yarns that, in combination, work to resist fabric pilling while minimizing stretch and creep. In one embodiment, the fabric is a textile fabric having at least three bar construction that is warp knitted, and is comprised of ground and pile yarns that are interlocked with one another and parallel to the fabric edge. The resulting stitches are arranged in horizontal rows, or courses, and vertical columns, or wales, formed by the knitting needles during one knitting cycle. In accordance with one embodiment, the pile yarns are multifilament, microdenier synthetic yarns. Microdenier yarns are generally regarded as being equal to or less that 1.1 denier for each filament. On the other hand the ground yarns are synthetic monofilament yarns, each filament of which is no less than 10.0 denier.
A knit polyester fabric tends to be hydrophobic, slow to absorb liquids, exhibits little or no wicking, holds stains, holds odors, and the like. Also, it is known in the fabric industry that polyester knit fabrics are easy to print on, hold dyes well, and the like.
Since polyester is hydrophobic, conventional wisdom would lead one to choose a cotton blend or a cotton fabric if they wanted a fabric which was absorbent. For example, a cleaning cloth would be made of a 100% cotton terry cloth or a cotton and polyester blend fabric. One would not typically use a polyester or synthetic knit fabric as a cleaning cloth since such fabrics tend to be hydrophobic, do not absorb water well, have poor wicking, low moisture retention, and the like.
Conventional cleaning cloths for wet or dry cleaning of household surfaces such as carpets, upholstery, clothing, furniture, floors, counter tops, and the like are usually made from cotton fabric or synthetic and cotton blend fabrics.
With respect to conventional absorbent articles such as diapers, it is commonly believed that one must use a cotton material or a cotton blend as an underlayer to absorb, wick, and retain liquids such as water or urine away from, for example, an open knit top layer. It is conventional wisdom that the absorbent underlayer must be cotton and that there must be an underlayer in addition to a top synthetic layer.
For example, adult incontinent undergarments or diapers may have an absorbent insert or area employing a combination of multiple layers of highly absorbent fabric with an open knit top layer making contact with the skin. The absorbent fabric layer, or layers, may be hydrophilic cellulosic fibers, cotton fabric, or the like.
Hence, there is a need for an improved polyester or synthetic fabric or product, and method which provides for enhanced absorbency, wicking, soil release, and/or odor removal and/or which is hydrophilic, absorbent, wicking, laundrable, cleanable, printable, non-fraying, dimensionally stable, colorfast, anti-pathogenic, and/or combinations thereof.
In accordance with one embodiment of the present invention, a chemically treated polyester microdenier knit fabric is provided which has enhanced wicking, moisture absorption, stain removal, and/or odor removal. The chemical treatment provides increased wicking action and moisture absorption and facilitates stain release and odor removal. The microdenier knit construction provides that the fabric will not fray after laundering, has increased surface area for improved print definition, greater surface area for increased moisture absorption and quick evaporation, and a unique loop structure which facilitates moisture transfer from the surface (quick absorption and instant wicking). The polyester fiber also provides heat transfer print capability, durability to successive industrial launderings, and retains its original shape and appearance.
In accordance with one test for wicking and moisture absorption of a treated polyester fabric, the wicking performance or rate of rise was 4xe2x80x3 at five minutes, 5.5xe2x80x3 at fifteen minutes, and 6.5xe2x80x3 at thirty minutes. The wet pickup was 356% at zero minutes, 206% at five minutes, 186% at ten minutes, 178% at fifteen minutes, and 164% at thirty minutes. The polyester microdenier knit fabric of the present invention instantaneously wicks moisture away from the surface and absorbs more than twice its weight in liquid. The chemical treatment also facilitates stain release and odor removal. The fabric may also be treated to provide anti-bacterial, anti-viral, anti-microbial, anti-fungal and/or anti-pathogenic agents to the fabric.
As described in U.S. Pat. No. 5,916,273 and in accordance with a preferred embodiment of the present invention, the pile yarns are warp knitted with extended underlaps between the stitches on the technical back, to provide significant yarn area. This yarn area is subsequently raised by napping, sanding, brushing, or any other method that raises and breaks the filaments to form a plush surface. The ground yarns are warp knitted in a dimensionally stable stitch pattern, predominantly on the technical face of the fabric, to resist stretch of the fabric in a direction parallel to the fabric edge. In a preferred embodiment, for. example, the pile yarns may be knitted in a 1-0, 4-5 stitch pattern, while the ground yarns are knitted in a 1-0, 0-1 and 1-0, 2-3 stitch pattern.
As described above, the pile yarns comprise the technical back of the fabric during fabric construction; however, after the pile yarns are raised to form a plush surface, the plush pile surface is considered the front or face of the finished fabric (absorbent, print receiving surface). Conversely, the ground yarns, which comprise the technical face of the fabric during construction, are considered the back or bottom of the finished fabric. Although it is preferred to use the pile side as the upper surface (it prints better and has a better appearance), it is contemplated that both surfaces of the fabric are absorbent and that either face may be used as the upper or lower surface as desired.
According to a further aspect of the invention, there is provided a fabric, product, article, composite, assembly, or the like having at least an upper surface which is absorbent, wicking, hydrophilic, printable, launderable, cleanable, and/or combinations thereof.